package Day2025_03_29;

import java.util.Scanner;

/**
 * 12届蓝桥杯 javaB 卡片
 */

public class Demo02 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        //在此输入您的代码...
        int n = scan.nextInt();
        int k = 0, tmp = 0, i = 1;
        while (true) {
            tmp += i;
            i++;
            k++;
            if (tmp >= n) break;
        }
        System.out.println(k);
        scan.close();
    }
}
